From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755568Ab3IMLCf (ORCPT ); Fri, 13 Sep 2013 07:02:35 -0400 Received: from mail-la0-f42.google.com ([209.85.215.42]:64107 "EHLO mail-la0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753784Ab3IMLCc (ORCPT ); Fri, 13 Sep 2013 07:02:32 -0400 Subject: [PATCH] shmem: fixup memory reservation during truncating To: Hugh Dickins From: Konstantin Khlebnikov Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Fri, 13 Sep 2013 15:02:24 +0400 Message-ID: <20130913110224.20826.74479.stgit@zurg> User-Agent: StGit/0.15 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Shared anon mappings created without MAP_NORESERVE may hold reservation of memory commitment for whole size of shmem segment. There was no way to change that size, but recently introduced 'map_files' in proc allows to do that. This patch adjust memory reservation in shmem_setattr() during truncating. Signed-off-by: Konstantin Khlebnikov --- mm/shmem.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/mm/shmem.c b/mm/shmem.c index ff08920..a15c8dd 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -148,6 +148,19 @@ static inline void shmem_unacct_size(unsigned long flags, loff_t size) vm_unacct_memory(VM_ACCT(size)); } +static inline int shmem_reacct_size(unsigned long flags, + loff_t oldsize, loff_t newsize) +{ + if (!(flags & VM_NORESERVE)) { + if (VM_ACCT(newsize) > VM_ACCT(oldsize)) + return security_vm_enough_memory_mm(current->mm, + VM_ACCT(newsize) - VM_ACCT(oldsize)); + else if (VM_ACCT(newsize) < VM_ACCT(oldsize)) + vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize)); + } + return 0; +} + /* * ... whereas tmpfs objects are accounted incrementally as * pages are allocated, in order to allow huge sparse files. @@ -607,6 +620,10 @@ static int shmem_setattr(struct dentry *dentry, struct iattr *attr) loff_t newsize = attr->ia_size; if (newsize != oldsize) { + error = shmem_reacct_size(SHMEM_I(inode)->flags, + oldsize, newsize); + if (error) + return error; i_size_write(inode, newsize); inode->i_ctime = inode->i_mtime = CURRENT_TIME; }